The present invention generally relates to the field of telecommunications. The invention relates more particularly to an apparatus and method for alerting and signal management of Call Waiting (CW) and/or Distinctive Call Waiting (DCW) located and used in conjunction with a plurality of Customer Premises Equipment (CPE).
The Call Waiting (CW) and Distinctive Call Waiting (DCW) telephony features are generally well known and have been offered by most Local Exchange Companies (LEC) to enhance a subscriber""s utilization of a single telephone line. In conventional CW, when a subscriber (first party), who has CW service, is engaged in a telephone conversation with a second party and a third party calls the first party, the subscriber receives a special audible call waiting tone called a Subscriber Alert Signal (SAS) that is typically 440 Hz for 300 milliseconds, whereas the third party receives an audible ringing tone. For the case of Distinctive Call Waiting (DCW), when a subscriber (first party), who has DCW service, is engaged in a telephone conversation with a second party and a third party calls the first party, the subscriber also receives a special audible distinctive call waiting tone also known as a Subscriber Alert Signal (SAS) that consists of sequenced, variable-length bursts of 440 Hz tones interspersed with variable length silent intervals. The total duration of the SAS can last up to a second. As well the third party receives an audible ringing tone. Upon receipt of the SAS the subscriber has the option of placing the existing call on hold and answering the incoming call or ignoring the incoming call. Answering the call is accomplished by a switch hook flash operation of a sufficient duration (300 to 1100 msec.) to signal to the LEC""s Central Switching Office Stored Program Control System (SPCS).
Telephone features such as CW and DCW, while convenient, will not work when the initial call comprises a data session, between a subscriber""s personal computer terminal and a host computer. Often the incoming CW and DCW signals just introduce errors to the data transmission session, and it is impractical to aurally monitor for the incoming signal, without the loss of the data session. With the popularity of the Internet it is not unusual for a situation to occur where a data session may last for hours and the calling third party continues to receive an audible ringing tone assuming the first party has CW or DCW. When this situation occurs, the calling party appears to ring endlessly and the called first party is not aware that a call is even being attempted. Due to improved modern error correction protocols and modem retraining, modems and Internet software have made data interruptions, caused by line dropouts and noise, transparent to an Internet user in that the user may even be unaware that a data interruption has occurred. Should the data interruption be severe enough, a user can reconnect to a TCP/IP connection very easily (typically with a click of a mouse button). When CW and DCW signals appear during a data session between modems they also may be treated as data interruptions with behavior similar to that described previously.
A form of CW and DCW alerting and signal management would be useful to allow the subscriber to transfer, in one operation, a telephone line from a first party (initial CPE) and a second party to a third party and another first party CPE. An example that best illustrates this concept is a data session between a (CPE) modem (first party) and a remote modem (second party) transferring to the calling party (third party) who could be using a telephone for voice communication to a CPE telephone (first party). Other examples of a transfer could be a calling FAX (third party) communicating with a CPE FAX (first party) or a calling (third party) telephone communicating with a CPE answering machine (first party). In all of these examples the first party has the option of ignoring the CW or DCW condition and continuing the data session in progress between the (CPE) modem (first party) and the remote modem (second party).
A prior art scheme for adapting a modem for the call-waiting feature is disclosed in U.S. Pat. No. 4,852,151 issued Jul. 25, 1989 and entitled MODEM WITH CALL WAITING. Another prior art scheme for adapting a modem for the call waiting feature is disclosed in U.S. Pat. No. 5,287,401 issued Feb. 15, 1994 and entitled APPARATUS AND METHOD FOR A MODEM FOR DETECTING A CALL WAITING SIGNAL. Both these prior art schemes adapt a modem and attempts to maintain the data session on hold while responding to a third party call. Another Prior art scheme for adapting a modem interface for the call waiting feature is disclosed in U.S. Pat. No. 4,995,074 issued Feb. 15, 1994 and entitled SWITCHED LINE MODEM INTERFACE SYSTEM. This prior art scheme adapts a modem interface and attempts to maintain the data session on hold while responding to a third party call.
One disadvantage to these prior art schemes is that they are not independent in that they must pass information or signals to a modem or modem interface. Another disadvantage to these prior art schemes is that they must operate with similar or compatible host modems or modem interfaces. It is not always possible to communicate with a similar or compatible host modem or modem interface. Yet another disadvantage to these prior art schemes is the added complexity of attempting to maintain the host modem capable of resuming the data session. For Internet data communication with an Internet Service Provider (ISP) a host ISP server typically shuts down a modem after a data interruption of more than 10 seconds anyway. If a data session is lost however it is very easy to re-connect to an ISP by typically by depressing a mouse button.
It is therefore an object of this invention to provide an improved method and apparatus to detect and alert a subscriber of a CW or DCW condition and allow a subscriber a choice to manage a data session by switching from a local modem to a telephonic device while activating a CW or DCW transfer to a third party or to ignore the CW or DCW condition and continue the data session. It is a further object of this invention to be independent of the type of telephonic devices connected to the invention. Such that it does not matter to the invention if a modem, FAX, answering machine or telephone or combinations of are connected to the invention in that the invention will work for voice communication as well as data communications applications.
Another example of a problem introduced with the popularity of the Internet is the situation where a Small Business Home Office (SBHO) wishes to host an Internet site by setting up a TCP/IP Internet Server at the business location. The SBHO also has a FAX or answering machine. A TCP/IP Internet Server would essentially be dedicated to a telephone line.
It is also an object of this invention to provide an improved method and apparatus to detect and automatically share and manage a subscriber line during a CW or DCW condition. In the example situation a SBHO could share a telephone line between the TCP/IP Internet Server and the FAX and the answering machine.
One drawback with CW and DCW is that during voice communication between a first party and a second party, and a third party is attempting to call, the SAS tones transmitted must be aurally monitored by the first party and acted upon. Situations can occur in a household, especially with children or adolescents, where the SAS tone is ignored and an important call is missed and the subscriber is unaware. The situation can also occur if a visitor is using a phone at a SBHO, is engaged in a conversation, hears the SAS tones but is unfamiliar with CW and DCW and an important call is missed.
It is yet another object of this invention to provide an improved method and apparatus to detect and alert a subscriber of a CW and DCW condition without depending upon anyone aurally monitoring the telephone receiver set and allowing a subscriber to perform other activities.
U.S. Pat. No. 4,852,151xe2x80x94July 1989 Dittakavi et al.:
U.S. Pat. No. 4,995,074xe2x80x94February 1991 Goldman et al.:
U.S. Pat. No. 5,287,401xe2x80x94February 1994 Lin.:
U.S. Pat. No. 5,327,493xe2x80x94May 1991 Richmond et al.:
U.S. Pat. No. 5,519,767xe2x80x94May 1996 O""Horo et al.:
U.S. Pat. No. 5,651,060xe2x80x94July 1997 Cohn et al.
Bellcore Technical Reference GR-30-CORE, Issue 1, December 1994. xe2x80x9cLSSGR: Voiceband Data Transmission Interface Section 6.6xe2x80x9d
Bellcore Technical Reference TR-TSY-000219, Issue 2, November 1988, xe2x80x9cCLASSSM Feature: Distinctive Ringing/Call Waitingxe2x80x9d. FSD 01-01-1110
Swartz, K. Barry, xe2x80x9cThe Analog Display Services Interfacexe2x80x9d. IEEE Communications Magazine, April, 1993
Teletone M-981 Precise Call Progress Tone Decoder Data Sheet, Teletone catalog 1997
The embodiment of the present invention is directed to overcoming the problems set forth above. In compendium, the invention comprises signal detection, alerting and switching management circuitry for use in voice and/or modem or FAX data sessions. The device is Customer Premises Equipment (CPE) and is connected to a telephone subscriber""s line from the Public Switched Telephone Network (PSTN).
A signal management device of the preferred embodiment of the present invention until the telephone interfaced to the device is picked up. Assuming a subscriber wants to answer the third party""s call by picking up this telephone (manual answer mode), a switching circuit is activated that mutes any CPE, such as, but not limited to, a local modem or FAX connected to the data port of the device and signals a switch-hook flash condition to the SPCS. This effectively puts the first session on hold, and effectively transfers from the interfaced CPE local modem or FAX, to another CPE connected to the voice/FAX port of the device, and allowing a call-waiting party to commence in conversation or a data-signal to be received.
If the user does not wish to accept the call, the user simply pushes the acknowledge button on the surface of the device and does not pick up the telephone connected to the device, thereby ending the alerting process, and continuing the essentially uninterrupted data session (modern high speed modems can respond to the call waiting signal as a line interruption).
If the user accepted the call, and upon hanging up the CPE connected to the voice/FAX port of the device, the user would have to re-dial the device plugged into the data port (typically this is accomplished by a press of a mouse button). The device can be set to automatic answer mode to allow a subscriber to share a telephone line with in-coming calls to a FAX or answering machine. For example sharing a line with a TCP/IP Internet Server. A switching circuit is activated that mutes any CPE, such as, but not limited to, a local modem or FAX connected to the data port of the device and disconnects it from the telephone line (hanging up) and transfers from the interfaced CPE local modem or FAX, to another CPE connected to the voice/FAX port of the device. Hanging up effectively terminates the data session and causes the third party""s call to power ring. Any device connected to the voice/FAX port such as a FAX or answering machine can then answer. Upon completion of these in-coming calls the device will switch the telephone line back to the data port. In the example stated the server would in turn auto-connect an outgoing call to a PPP or SLIP connection for IP access, and automatically resume the data session where it was interrupted.
An aspect of the present invention is to provide a signal detection, alerting and switching management device, of the general character described, which is easy to use. Another aspect of the present invention is to provide signal detection, alerting and switching management device of the general character described, which is relatively low in cost. Another aspect of the present invention is to provide a signal detection, alerting and switching management device of the general character described which permits a single telephone line subscriber utilizing the telephone network for a data transmission, to employ a telephone feature such as distinctive call-waiting to answer a distinctive incoming caller, or the option not to answer, without terminating the data session. Yet another aspect of the present invention is to provide a signal detection alerting and switching management device of the general character described which does not require additional programming of a users"" computer terminal. A further consideration of the present invention is to provide signal detection, alerting and switching management device of the general character described, which is subscriber accessed by conventional telephone operation. Thus it will be seen, that there is provided a signal detection, alerting and switching management device which achieves the various aspects, features and considerations of the present invention, and is well suited to meet the conditions of practical usage. Other aspects, features and advantages of the present invention in part will be obvious. With these ends in view, the invention finds embodiment in the certain combinations of parts by which the aspects and features and considerations are attained, all as described with reference to the accompanying drawings, and the scope of which is pointed out, and indicated in the appended claims.